The order from the South Coast Air Quality Management District comes after recent tests showed that Exide Technologies is posing a health danger to as many as 110,000 people in neighboring cities.

A battery recycling plant in Vernon is being told to reduce its emissions after recent tests showed it is posing a danger to as many as 110,000 people living in an area that extends from Boyle Heights to Maywood and Huntington Park.

The South Coast Air Quality Management District announced late Friday that Exide Technologies, one of the largest battery recyclers in the world, must also hold public meetings later this spring to inform residents that they face an increased cancer risk and outline steps being taken to reduce it.

Air district officials said Exide's most recent assessment showed a higher cancer risk affecting a larger number of residents than any other of the more than 450 regulated facilities in Southern California over the 25-year history of a program to monitor toxic air contaminants. The primary contaminant in this case was arsenic.

There has been "nothing close to this ... never," said Sam Atwood, spokesman for the air district.

In a statement, Exide officials said they planned to work with the district on emissions reductions "that we expect will meet or exceed" requirements.

"Exide takes its environmental responsibilities seriously," the statement said, adding that the facility has cut its emissions of lead "extensively" over the last three years and plans additional modifications to reduce arsenic emissions.

Still, Maywood City Councilman Felipe Aguirre said he was furious at the news.

"I can't believe it. It's incredible," he said, adding that he has long suspected that the working-class immigrant residents in his town suffer more than their fair share of health problems because of polluting facilities in the area. "People are very sick."

Exide has been operating its 15-acre plant about five miles southeast of downtown Los Angeles since 1922. Every day the plant recycles about 41,000 batteries — including car batteries — salvaging lead and plastic instead of sending it to landfills.

A January report the company submitted to the air district, however, showed that emissions from the plant have elevated the cancer risk to people nearby to a point where approximately 156 cancer cases per million people can be expected to develop, mostly because of arsenic. For residents living a bit farther away in neighborhoods such as Boyle Heights, that risk is about 22 per million, according to air district officials. Those risks assume exposure over decades.

Under air district regulations, when cancer risk from a facility reaches 10 per million, public notification is required. When it hits 25, facilities must take steps to reduce their emissions.

Since 1987, when the Toxic Hot Spots program went into effect, only about 20 facilities in Southern California have ever reported risks that were greater than 25 in 1 million, Atwood said.

More than 95% of the facilities the air district regulates have risks under 10 in 1 million.

Exide is required to submit a "risk reduction plan" to the air district within 180 days. Within the next few months, it also must set up public meetings to discuss the situation.

If the company fails to comply with AQMD's conditions, it could face fines of up to $25,000 a day and, ultimately, a court order to shut down.

This is not the first time the air district has taken action against Exide. In 2008, officials ordered the company to cut lead emissions, saying the plant was posing unacceptable health risks. After that, the company made improvements such as enclosing facilities and installing negative air-pressure systems.

Barry Wallerstein, executive officer of the air district, said officials are working with the company to take "immediate steps to reduce their emissions and associated risks." He added that he wants the company to "follow a strict timeline to implement a long-term solution."

Boyle Heights resident Leonardo Vilchis, director of the community group Union de Vecinos, called the latest news about the company "terrifying."

"With so much pollution around the area, in the air and water, people are always having problems. It's terrifying to know the risks people are exposed to from just one company," he said.